Generally, polyester, particularly polyethylene terephthalate (hereinafter, referred to as PET) is chemically stable due to its stable structure and has high physical and mechanical strength and excellent heat-resistance, durability, chemical-resistance, and dimensional stability, such that the polyester has been widely used in various medical and industrial fields in addition to a packaging material. Recently, in order to impart various functionalities to a PET film, a method of manufacturing a copolyester film, a method of performing corona-treatment and applying a chemical material on a surface of the film, or the like, may be variously applied. Among them, a method of applying a chemical material to impart a new function to the surface of the film has been widely used.
Examples of the most representative functions of a polyester film of which a primer having a function is applied on a surface as described above may include: first, a printing adhesion function for improving a printing property between ink and the polyester film; second, an adhesion function for imparting an adhesion property with material to be applied in order to manufacture post-processing products having various specific functions, for example, an overhead projector (OHP) film, an exclusive graphic film for a laser or inkjet printer, or a diazo film; third, a heat sealing function for being used in laminating various packages; and fourth, an antistatic function that is essential to protect various graphic films and electronic materials. In addition, a releasing function of facilitating separation between the polyester film and the chemical applied thereonto, a slippery function for improving workability, and the like, are also included therein.
As a technical method of suppressing static electricity from being generated in the film as described above, there are an internal addition method of mixing an organic phosphate salt, or the like, at the time of manufacturing the film, a metal deposition method of depositing a metal compound on a surface, a method of applying a conductive inorganic particle onto the surface, a method of applying an anionic or cationic monomer compound or a polymer compound onto the surface, and the like. Among them, the internal addition method has disadvantages in that excellent physical properties of the film itself may be deteriorated, and it is difficult to uniformly implement an antistatic function. In addition, the method of treating the surface with the conductive polymer (conductive inorganic particles) and metal oxides has been prominent in view of excellent antistatic function, but a manufacturing cost of raw materials is excessively high while a solid content is excessively small, such that this method is restrictively used only for protecting an expensive electronic material. Meanwhile, the method of applying an anionic or cationic antistatic agent has been widely applied due to a relatively excellent antistatic effect and advantages in view of a manufacturing cost such as low manufacturing cost of raw materials, but there are problems such as aging characteristics and transferring to a rear surface caused by movement of the antistatic agent on the surface, thermal instability of a low molecular weight material, blocking, or the like. Therefore, various researches to overcome these problems have been conducted.
For example, as technologies associated with a method of applying a conductive polymer, an antistatic film coated with a primer layer containing the conductive polymer and a polyester-based emulsion as a binder has been disclosed in Korean Patent Laid-Open Publication No. 2008-0055266 (Jun. 19, 2008), and a conductive polymer type composition and film for pollution-proof and antistatic property containing a polyurethane binder resin having a silicone-based functional group has been disclosed in Korean Patent Laid-Open Publication No. 2010-0079587 (Jul. 8, 2010). In addition, as technologies associated with a method of applying an anionic or cationic low molecular weight antistatic agent, a heat shrinkable polyester film applied with a compound containing an anionic antistatic agent and a binder resin and having excellent antistatic performance has been disclosed in Korean Patent Laid-Open Publication No. 2007-0080332 (Aug. 10, 2007), and among polyester films having heterogeneous coating layers on both surfaces, a polyester film composed of an good-adhesive coating layer on one surface and a sulfonic acid-based cationic antistatic layer on the other surface of the base layer has been disclosed in Korean Patent Laid-Open Publication No. 2009-0104592 (Oct. 6, 2009).
A demand for these antistatic films has rapidly increased in accordance with the recent trends toward the growth of a display industry.
However, in the case of films according to the related art, after manufacturing the film, the film is delivered in a state in which the film is wound around a paper tube in a roll form. In this case, an antistatic agent in an antistatic layer may be transferred to a rear surface, which may cause problems in that a printing property is deteriorated at the time of performing a post-processing process such as a printing process, or the like. Therefore, an good-adhesive antistatic film capable of preventing the antistatic agent from being transferred to the rear surface and having excellent adhesive force with other base materials has been demanded.
More specifically, in accordance with the growth of a printing industry in which working is performed in an off-sheet scheme (in which the printing is performed on the sheet one by one in a state in which a plurality of sheets are overlapped with each other) and a market of a phototool material used to manufacture an electronic electric circuit, a demand of the good-adhesive antistatic film for improving adhesive force with a material such as silver halide, or the like, and controlling an electrification property to be generated during the use has also increased, which also increased a demand for the antistatic film.